I highly recommend getting a factory service manual for your year of truck. For Dodge's, the Chilton's manual leaves a lot to be desired; I would assume it is the same for Ford. As far as long block or replacement motor, I would do a rebuild on your stock block by a reputable shop or consider a replacement from another truck or from Ford/International. I don't think I'd get a replacement longblock from the typical chain rebuilders. My dad had two in a row go south on him in his 93 Chevy with a 6.5. Not apples to apples, but it is my .02.